• Journal of Advanced Marine Engineering and Technology
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• v.35 no.1
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• pp.75-81
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• 2011

Dissimilar joining of aluminum 6061-T6 alloy to aluminum 5083-O alloy was performed using friction-stir welding technique. The mechanical properties, hardness, macro- and micro-structure on dissimilar friction-stir-weld aluminium alloy were investigated. Mechanical properties of the weld mainly depend on which Al alloy is placed at the retreating sides of the rotating tool respectively during dissimilar friction-stir weld because the microstructure of stir zone was mainly composed of welded Al alloys of the retreating side. Onion ring pattern was observed like lamella structure stacked by each Al alloy in turn. It apparently results in defect-free weld zone that traverse speed was changed to 124 mm/min under conditions of tool rotation speed like 1250 rpm with 5 mm of tool's prove diameter, 4.5 mm of prove length, 20 mm of shoulder diameter, and $2^{\circ}$ of tilting angle. The 231 MPa of ultimate stress and the 121 MPa of yield point are obtained about the friction-stir-welded Al 6061-T6(AS) to Al 5083-O(RS).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.27-33
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• 2019

The aviation industry has grown beyond the simple processing and assembling of aircraft parts and now designs and exports finished aircraft. In this study, the vertical CNC milling rotational speed and feed rate were parameters to investigate the life of tools according to their shape: (flat, round, and ball end mill) in the rough cutting of titanium. These tools are widely used in aircraft manufacturing and assembly. The purpose of this study is to measure the cutting temperature generated during the cutting process and calculate the rate of tool wear. This will be accomplished by measuring the tool weight before and after cutting the specimen and to compare it with the results of previous studies. Our study showed that the maximum cutting temperature increased as cutting time, tool rotational speed, and feed rate increased. The highest cutting temperatures were recorded for the ball, round, and flat end mill, respectively. Tool wear for the ball, round, and flat end mill increased as the speed and feed rate increased. The flat end mill exhibited the highest rate of wear from a minimum of 0.62% to a maximum of 2.88%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.614-618
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• 2018

The changes in the mechanical properties according to the width of the tool shoulder, rotation speed and moving speed in friction stir welding (FSW) are evaluated using Al 6061-T6. The results indicated that the tensile strength value increases with increasing rotation speed. The higher the moving speed of the tool shoulder, the lower the tensile strength, regardless of the tool type. A higher tensile strength value was generally obtained with a tool shoulder diameter of 12mm (TSD12) than with 8mm. When the moving and rotation speeds exceed a limiting value, a stabilization stage is reached, in which (the tool shoulder diameter?) no longer affects the material properties. At a tool shoulder diameter of 8mm (TSD8), the material properties are decreased and the mixture of material in the welding area is incomplete in comparison with the tool type of TSD12. The tensile strength value is decreased at a rotation speed of 1500 rpm. As a result, a rotation speed higher than the threshold value is needed in order for and the transition temperature to be reached, which allows the complete mixing of the material in the welding area.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.5-17
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• 1995

기술과 과학이 끊임없이 발달되고 있는 가운데 생산기술과 생산공업도 비약적으로 발달되고 있다. 공작기계에 대한 요구사항은 일반적으로 고정도화, 고속도화 그리고 고능률화 나아가서는 자동화이다. 다시 말해서 더욱 좋은 품질(고정도화)과 저렴한 가격(고능률화)의 제품을 빨리 사용자에게 공급(고속화)할 수 있고, 다양한 제품을 만들 수 있는 공작기계가 요구되는 것이다. 고능률화 또는 고속화를 위해서는 고속절삭가공을 실현해야하며 그러기 위해서는 Spindle(주축)의 회전수를 높이고 각 축의 이송 속도가 빨라야 되며 절삭 이송을 고속화하여야 한다. 그리고, 머시닝센터에서는 공구를 자동으로 교환하는(ATC)을 신속히 해야 한다. 이와 같은 고속 공작기계에 대한 요구는 점점 많아지고 있으며 공작기계전시회가 열릴때마다 고속도화는 점점 진전되고 있다. 최근에는 주축의 회전수가 10,000$min^{-1}$은 보통이고 최고 40,000$min^{-1}$이상에 도달하고 있다.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.332-341
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• 1998

Conventional polishing of stone panel edges has been done by hand. While this has changed somewhat with the advent of automatic machines, it is still very much a hand finishing technology. For the development of edge shape milling tool, the primary test on characteristics of edge shape milling tool was carried out. This paper presents the results of tests focused upon the milling capability that was varied by the variables of operation parameters. Author tried to confirm the effect of six operation parameters of equipment such as rotation speed, advance speed, applied load, water flow rate and rotational direction. The result from test was described in term of shape milling capability that was defined as cutting volume of rock by unit weight of tool wear. The variance of the results could indicate the optimum level of each operating parameters. The test was also carried out to determine the abrasion resistance varied according to the abrasive flow rate. The abrasion resistance was increased with the abrasive flow rate, but over some rate it was not changed.

• Tunnel and Underground Space
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• v.30 no.3
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• pp.181-192
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• 2020

Pin-on-disk test is a suggested abrasion testing method by ASTM (American Society for Testing and Materials). This briefly illustrated the Archimedean spiral motion of a pin type specimen on a disk. To apply this method to rock cutting tools, a constant linear velocity (CLV) is precisely maintained during the test. We defined the two velocity vectors (RPM and horizontal speed) which connected to the resultatnt velocity. We derived a differential equations for the two parameters under CLV condition. It was difficult to find a exact solution. Previous literatures had been reviewed, and an approximate solution was investigated. We mathematically simulated the result for a certain parameter, and examine the accuracy of the solution.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.4
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• pp.425-431
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• 2016

The usage of Friction Stir Welding(FSW) technology has been increasing in order to reduce the weight in automobile industries. Previous studies that investigated on the FSW have focused on the aluminum alloy. In this study, Al6061-T6 alloy plates having 5 mm of thickness were welded under nine different conditions from three tool rotation speeds: 900, 1000 and 1100 rpm, and three feed rates: 270, 300 and 330 mm/min. Specimen size of Micro Shear Punch(MSP) test was $10{\times}10{\times}0.5mm$. The mechanical properties were evaluated by MSP test and Analysis of Variance (ANOVA). The specimens were classified by advancing side(AS), retreating side(RS), and center(C) of width of tool shoulder. The optimal welding condition of FSW based on micro strengh was obtained when the tool rotation speed was 1100 rpm and the feed rate was 300 mm/min. The maximum load measured AS, RS, and C in the weldment was measured 554.7 N, 642.9 N, and 579.2 N, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.1
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• pp.84-89
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• 2013

Titanium used in industry has been widely applied for aerospace engine, structures and spacecraft exterior, etc. because the titanium is higher in strength compared to the steel and light in weight compared to the steel. This study is to investigate the effect of cutting depth and cutting time on the spindle speed and feed rate of vertical machining center as a parameter to find the rough cutting time and cutting depth in the medium speed cutting machining of the titanium alloy. It is found that the cutting machining heat are increased as the cutting depth, feed rate, cutting time and spindle speed are raised.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.211-212
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• 2009

국내의 다이아몬드 마이크로 블레이드 산업의 경우 충분한 이론적 검증을 거치지 못하고 종전의 경험 및 외산품에 대한 분석을 토대로 제작된 제품에 간단한 물성만을 체크하여 업체에 공급한다 해도 과언이 아니다. 이러한 국내의 실정을 인지하여 본 연구에서는 Cu와 Sn을 주 결합재로 사용한 다이아몬드 마이크로 블레이드에 있어 고체윤활제인 흑연과 $MoS_2$의 첨가에 따른 마모 특성을 비교하였다. 마모시험의 분위기는 상온에서 건식 분위기로 진행 되었으며, 그 결과 흑연을 첨가할 경우 가장 높은 마찰감소를 보임을 확인할 수 있었다. 이번 연구는 상온 및 저 회전 속도에서의 사용을 목적으로 한 다이아몬드공구의 연구 자료로 활용될 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.251-255
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• 2017

Burr generation is inevitable during the machining of a micro-pattern, and it is difficult to distinguish between the pattern and burr because they have a very small dimensions. In this study, a micro-pattern with a pitch of $60{\mu}m$and height of $1{\mu}m$ was fabricated on a cylindrical surface using a turning machine. The structure of a burr and its generation mechanism were determined, and a magnetic abrasive deburring process was used to improve the accuracy of the pattern. As a result, when fabricating a micro-pattern, it was shown that the direction of the burr was determined by the feed direction of the tool. The measured pattern height was $1.018{\mu}m$ when the magnetic flux density and spindle speed were respectively 40 mT and 1600 rpm, respectively, during magnetic abrasive deburring, which were determined to be the optimal conditions for processing.